Varialvus gen. nov. [Digenea, Cryptogonimidae], from species of Lutjanidae [Perciformes] off the Great Barrier Reef, New Caledonia and the Maldives

A survey of the cryptogonimid trematode fauna infecting Indo-West Pacific Lutjanidae (Perciformes) revealed the presence of four new species whose morphological and genetic differences relative to all other known cryptogonimids warrants the proposal of a new genus, Varialvus gen. nov. Species of this new genus were recovered from sites off Heron and Lizard Islands on the Great Barrier Reef, Australia, New Caledonia and Rasdhoo Atoll, Maldives. Varialvus gen. nov. is distinguished from all other cryptogonimid genera by the combination of a fusiform to oval body, the relatively small number of large oral spines, a median ovary which is relatively condensed and highly lobed, opposite to slightly oblique testes, uterine loops that are restricted to the hindbody and extend well posterior to the testes, and vitelline follicles that are mainly in the forebody but may extend from the anterior margin of the ovary to anterior to the intestinal bifurcation. Bayesian inference analysis of partial large subunit (LSU) rDNA sequence data for these species revealed that they formed a monophyletic clade, despite V. charadrus sp. nov. having a distinctly muscular gonotyl, which based on morphological characters alone may have warranted placement in a separate genus in the absence of DNA sequence data. At least one species of Varialvus gen. nov. is apparently widespread in the Indo-West Pacific. Three species, V. lacertus sp. nov., V. jenae sp. nov. and V. angustus sp. nov. have each been found at only one locality, but V. charadrus sp. nov. was recovered from lutjanids off the Great Barrier Reef, New Caledonia and the Maldives, demonstrating a biogeographic range of at least 10,000 kilometres. Siphoderina lutjani (Saoud, Ramadan et Al Kawari, 1988) Miller et Cribb, 2008 is transferred here as V. lutjani (Saoud, Ramadan et Al Kawari, 1988) n. comb. based on morphological and host group agreement with species of Varialvus gen. nov.